Regarding Trump's claim about taxes, Amazon paid $167 million in income taxes in 2014 -- the first full year after Bezos acquired the paper. And that was despite the fact that Amazon reported a pre-tax loss in 2014.

And in the first nine months of this year, Amazon has paid $498 million in income taxes and reported pre-tax income of $630 million.

So Trump is wrong when he said that Amazon is unprofitable.

"It doesn't make any sense," said Martin Sullivan, chief economist with Tax Analysts.

To be sure, Amazon doesn't have a squeaky clean image with regards to taxes.

It has been targeted in probes in Europe for allegedly paying lower taxes there than it should. It agreed earlier this year to pay taxes in more European nations. It had previously only been doing so in tiny Luxembourg.

Amazon isn't the only big American company accused of dodging taxes abroad either. Apple(AAPL) and Starbucks(SBUX) have come under fire in Europe too.

But nobody in Europe has accused Amazon of using Bezos' personal investment in a media company to lower its tax bill.

Amazon had no comment about Trump's allegations.

Its stock has more than doubled this year. That is mainly a reflection of Amazon's growing dominance in online retail and its emergence as a cloud computing giant, and not because of what it does or doesn't pay in taxes.